1. Field of Invention
The invention relates to a method and an appliance for regulating the inflow of hot water to a container.
2. Description of Related Art
Demands for defined volumes of liquids of specific temperature is an objective in various applications. These areas include private households, for example, in bathrooms and kitchens, the service trades, such as catering, industry, in particular the chemical and food industry, in agriculture and in the public sector, including the health service. In general, for this purpose, part volumes with a forward flow having a lower temperature than the desired (or target) temperature (referred to as mixing temperature below) and part volumes with a forward flow having a higher temperature than the desired temperature (mixing temperature) are mixed with one another. In most cases, the liquids are water or aqueous solutions, and therefore this case is described below. However, all the designs may be extended to virtually any liquids.
Mixing appliances, also referred to in the sanitary sector as mixing taps or mixing batteries, which at the outflow control a defined mixing temperature with the aid of a control which has actuators for setting the throughflow volumes (flowrate) of a hot and cold water supply line as a function of the instantaneous mixing temperature determined by means of a temperature measuring device, are described, for example, in DE-A-3,546,550 and the corresponding U.S. Pat. No. 4,693,415.
An appliance and a method of the type initially mentioned, which, in addition to a control of the mixing temperature, also provide a specific overall volume, and are known, for example, from EP-A-1,249,544 and the corresponding U.S. Pat. No. 6,473,917 B2. In this case, the part volume which has flowed out is measured by means of a flowrate measuring device installed in the mixing water line upstream of the outflow or via a device for detecting the filling level in a collecting container and is compared with the predetermined overall volume.
The method and appliances described are in this case based on the assumption that, when the mixing temperature of the outflowing liquid is being regulated, the overall volume which has flowed out (also referred to as the desired volume) also possesses this mixing temperature. In practice, however, the desired temperature of the overall volume deviates from the mixing temperature of the outflow. This is due, for example, to heated or cooled liquids in the inflow lines, sudden pressure changes and, consequently, also flowrate changes in the inflow lines, and transient phenomena in the control and regulating circuits. Deviations of the mixing temperature from the desired temperature which are caused thereby lead in total to the deviation observed in practice.